Alloy



Patented Oct. 2, 1934 UNITED STATES PATENT OFFICE mesne assignments, toMagnesium Development Corporation, a corporation of Delaware No Drawing.Application January 4, 1934, Serial No. 705,285

2 Claims.

The invention relates to magnesium base alloys. An object of theinvention is the development of alloys of this nature containing tin andcobalt.

I have discovered that when cobalt is added to magnesium base alloyscontaining tin, the resulting alloys undergo an improvement in bothtensile strength and elongation. I have also discovered that themagnesium-tin-cobalt alloys may be further improved by suitable thermaltreatments.

As an illustration of the effect produced by the addition of cobalt to amagnesium base alloy, 1,.

have made up an alloy of this nature containing 5.0 per cent of tin, thebalance being commercial magnesium. This alloy had a tensile strength,in the cast condition, of 18,380 pounds per square inch and anelongation of 5.0 per cent in two inches. A second alloy containing, inaddition to 5.0 per cent of tin, 0.5 per cent of cobalt had in the castcondition a tensile strength of 18,940 pounds per square inch and anelongation of 5.7 per cent in two inches. A third alloy containing 2.0per cent ofcobalt, in addition to 5.0 per cent of tin, had in the castcondition a tensile strength of 20,920 pounds per square inch and anelongation of 6.3 per cent in two inches. It may be observed that theabove additions of cobalt have successively increased both strength andelongation.

A thermal treatment of 19 hours at 525 centigrade followed by quenchingincreased the strength of the 0.5 per cent cobalt alloy from 18,940pounds to 23,680 pounds per square inch and the elongation from 5.7 percent to 8.8 per cent in two inches. After the same thermal treatment thetensile strength of the-2.0 per cent cobalt alloy increased from 20,920pounds to 24,670 pounds per square inch and the elongation increasedfrom 6.3 per cent to 9.2 per cent in two inches.

Another magnesium-tin alloy containing 10.0 per cent -of tin, thebalance being commercial magnesium, was made up tocontain, in addition,

1.0 per cent of cobalt. This alloy on being heated for 19 hours at 525centigrade and quenched had a tensile strength of 23,220 pounds persquare inch and an elongation .of 7.8 percent in two inches. After anadditional aging treatment of 20 hours at 150 centigrade the tensilestrength C9 increased to 26,750 pounds per square inch and theelongation to 9.8 per cent in two inches. In alloys of the type hereindiscussed the cobalt may be present in amount between about 0.1 per centand 4.0 per cent and may be added to magnesium-tin alloys containingfrom about 0.1 per cent to about 20.0 per cent of tin. As a preferredcomposition I have used an alloy containing 5.0 per cent of tin and 1.0per cent of cobalt, the balance being commercial magnesium.

The alloys are susceptible to variations in their physical properties bythermal treatments at temperatures most effective between about 425 and525 centigrade and may be given additional aging treatments betweenabout 100 and 200 centigrade. They may be compounded in any of the waysfamiliar to the art, such as by adding to the molten magnesium bath thealloying element when its melting point is below that of the magnesium,or approximates it, or by adding the 8 alloying element in the form of amagnesiumrich alloy or hardener when its melting point considerablyexceeds that of the magnesium.

The alloys disclosed herein may be extruded over the whole rangedisclosed, and may be forged or otherwise mechanically deformed when theamountof added alloying elements does not become too great a proportionof the whole.

In this specification and the appended claims the term magnesium basealloy signifies an alloy containing more than 50 per cent magnesium.

I claim:

1. A magnesium base alloy containing from 0.1 per cent to 20.0 per centof tin and from 0.1 per cent to 4.0 per cent of cobalt, the balancebeing substantially all magnesium.

2. A magnesium base alloycontaining about 5.0 per cent of tin and 1.0per cent of cobalt, the balance being substantially all magnesium.

' f ROY E. PAINE.

